Core 2 - Driving Biological Projects Three DBPs were selected for the initial 3 years, with primary collaborations representing geographically diverse institutions. These will be replaced in Year 4 by new DPBs, in which a wider array of institutions will be represented. B.1.DBP1 Molecular Phenotyping of Kawasaki Disease Kawasaki disease (KD) is a self-limited, acute vasculitis that is the most common cause of acquired heart disease in children. Coronary artery aneurysms occur in up to 25% of untreated children, but can be prevented by timely administration of high dose intravenous immune globulin (IVIG). While the etiology is unknown, an infectious agent that triggers an immunologic reaction in genetically susceptible hosts is suspected. Genotyping of haplotyped-tagged single nucleotide polymorphisms (SNPs) has identified genetic variation in the pathways for TGFp and calcineurin/NFAT that influence disease susceptibility and outcome. The biomedical researchers face a number of dilemmas: 1. There is no diagnostic test for the condition to aid in the recognition of affected children, and the clinical syndrome can mimic other, more common infectious diseases of children that do not require specific therapy. 2. Treatment with IVIG must be administered eariy in the course of the vasculitis to prevent permanent damage to the cardiovascular system. While most children will respond to IVIG, approximately 20-30% will have persistent or recrudescent fever and inflammation, will require additional therapy, and will be at increased risk of developing coronary artery abnormalities. 3. Tools need to be created to risk stratify patients and to convert molecular data into clinically useful phenotypes that can guide therapy.